1. Field of the Invention
This invention relates to document image processing, and in particular, it relates to background removal for document images.
2. Description of Related Art
It is not uncommon that some document images have background for texts. For example, sometimes presentation slides are made with background graphics. Such images can be challenging for many binarization methods, whether they are global or local/adaptive methods. Global binarization methods may produce all white or all black for the regions with background, while local/adaptive binarization methods may introduce artifacts in the transition zones between regions with and without background and in zones where the background image has significant variations. Various sophisticated background removal techniques have been proposed, but they tend to be complex and slow. In addition, some background removal techniques, for example contrast mapping such as that disclosed in U.S. Pat. No. 6,731,821, use a global approach that has impact on foreground texts and graphical (non-text) regions while removing background.